| Message ID | 0e0b1859-e7f8-3f8d-2be8-e0069b116525@suse.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | x86/PVH: restore VMX APIC assist for Dom0 | expand |
On Tue, Aug 23, 2022 at 01:56:22PM +0200, Jan Beulich wrote: > --- a/xen/arch/x86/hvm/dom0_build.c > +++ b/xen/arch/x86/hvm/dom0_build.c > @@ -55,6 +55,9 @@ > */ > #define HVM_VM86_TSS_SIZE 265 > > +bool __initdata opt_dom0_assisted_xapic = true; > +bool __initdata opt_dom0_assisted_x2apic = true; Defaulting those to true unconditionally is troublesome, as the check in arch_sanitise_domain_config() will fail if either assisted_x{2,}apic_available is not true, and dom0 domain creation will fail, so... > + > static unsigned int __initdata acpi_intr_overrides; > static struct acpi_madt_interrupt_override __initdata *intsrcovr; > > --- a/xen/arch/x86/include/asm/setup.h > +++ b/xen/arch/x86/include/asm/setup.h > @@ -68,6 +68,14 @@ extern bool opt_dom0_verbose; > extern bool opt_dom0_cpuid_faulting; > extern bool opt_dom0_msr_relaxed; > > +#ifdef CONFIG_HVM > +extern bool opt_dom0_assisted_xapic; > +extern bool opt_dom0_assisted_x2apic; > +#else > +#define opt_dom0_assisted_xapic false > +#define opt_dom0_assisted_x2apic false > +#endif > + > #define max_init_domid (0) > > #endif > --- a/xen/arch/x86/setup.c > +++ b/xen/arch/x86/setup.c > @@ -784,6 +784,11 @@ static struct domain *__init create_dom0 > > dom0_cfg.arch.emulation_flags |= > XEN_X86_EMU_LAPIC | XEN_X86_EMU_IOAPIC | XEN_X86_EMU_VPCI; > + > + if ( opt_dom0_assisted_xapic ) > + dom0_cfg.arch.misc_flags |= XEN_X86_ASSISTED_XAPIC; > + if ( opt_dom0_assisted_x2apic ) > + dom0_cfg.arch.misc_flags |= XEN_X86_ASSISTED_X2APIC; ...the values of assisted_x{2,}apic_available need to be taken into account here in order to avoid requesting an invalid configuration. I could swear I have checked PVH dom0 interaction when reviewing the original patch, but I clearly missed it. Thanks, Roger.
--- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -753,7 +753,8 @@ Specify the bit width of the DMA heap. ### dom0 = List of [ pv | pvh, shadow=<bool>, verbose=<bool>, - cpuid-faulting=<bool>, msr-relaxed=<bool> ] + cpuid-faulting=<bool>, msr-relaxed=<bool>, + assisted-xapic=<bool>, assisted-x2apic=<bool> ] Applicability: x86 @@ -814,6 +815,10 @@ Controls for how dom0 is constructed on If using this option is necessary to fix an issue, please report a bug. +* The `assisted-xapic` and `assisted-x2apic` options, defaulting to true, + allow disabling of the respective hardware assists. These are applicable + to PVH Dom0 only, and their effect is limited to VT-x. + ### dom0-cpuid = List of comma separated booleans --- a/xen/arch/x86/dom0_build.c +++ b/xen/arch/x86/dom0_build.c @@ -293,6 +293,12 @@ static int __init cf_check parse_dom0_pa opt_dom0_cpuid_faulting = val; else if ( (val = parse_boolean("msr-relaxed", s, ss)) >= 0 ) opt_dom0_msr_relaxed = val; +#ifdef CONFIG_HVM + else if ( (val = parse_boolean("assisted-xapic", s, ss)) >= 0 ) + opt_dom0_assisted_xapic = val; + else if ( (val = parse_boolean("assisted-x2apic", s, ss)) >= 0 ) + opt_dom0_assisted_x2apic = val; +#endif else rc = -EINVAL; --- a/xen/arch/x86/hvm/dom0_build.c +++ b/xen/arch/x86/hvm/dom0_build.c @@ -55,6 +55,9 @@ */ #define HVM_VM86_TSS_SIZE 265 +bool __initdata opt_dom0_assisted_xapic = true; +bool __initdata opt_dom0_assisted_x2apic = true; + static unsigned int __initdata acpi_intr_overrides; static struct acpi_madt_interrupt_override __initdata *intsrcovr; --- a/xen/arch/x86/include/asm/setup.h +++ b/xen/arch/x86/include/asm/setup.h @@ -68,6 +68,14 @@ extern bool opt_dom0_verbose; extern bool opt_dom0_cpuid_faulting; extern bool opt_dom0_msr_relaxed; +#ifdef CONFIG_HVM +extern bool opt_dom0_assisted_xapic; +extern bool opt_dom0_assisted_x2apic; +#else +#define opt_dom0_assisted_xapic false +#define opt_dom0_assisted_x2apic false +#endif + #define max_init_domid (0) #endif --- a/xen/arch/x86/setup.c +++ b/xen/arch/x86/setup.c @@ -784,6 +784,11 @@ static struct domain *__init create_dom0 dom0_cfg.arch.emulation_flags |= XEN_X86_EMU_LAPIC | XEN_X86_EMU_IOAPIC | XEN_X86_EMU_VPCI; + + if ( opt_dom0_assisted_xapic ) + dom0_cfg.arch.misc_flags |= XEN_X86_ASSISTED_XAPIC; + if ( opt_dom0_assisted_x2apic ) + dom0_cfg.arch.misc_flags |= XEN_X86_ASSISTED_X2APIC; } if ( iommu_enabled )
I don't expect it was intended to default PVH Dom0 to "no assist" mode. Introduce command line (sub-)options allowing to suppress enabling of the assists, paralleling the guest config settings for DomU, but restore the defaulting to "enabled". Fixes: 2ce11ce249a3 ("x86/HVM: allow per-domain usage of hardware virtualized APIC") Signed-off-by: Jan Beulich <jbeulich@suse.com> --- Besides the issue caused here (the manifestation of which appears to correlate with the other fallout Andrew is trying to deal with) I'm observing further warnings, but I guess these have been there for some time (perhaps forever): When parsing AML and encountering the objects describing the CPUs, Linux would find entries with the original APIC IDs. If those don't match the ones we assign in pvh_setup_acpi_madt(), the kernel will wrongly consider the entries to describe further CPUs, which it therefore would deem hot-pluggable. This again results in warnings, this time "NR_CPUS/possible_cpus limit of ... reached".